THE PRINCIPLES OF FISH SALTING 367 



are so prepared, except for export trade. At least 2 diflFerent species of bacteria pro- 

 duce reddening of cod: One of these is a spirochete which in colonies is pale 

 pink; the other is a bacillus whose colonies are deep red. These bacteria are 

 particularly resistant to salt and live and grow on moist salt or strong salt solu- 

 tions. Mixed colonies of these bacteria are often found varying in color from pale 

 pink to deep red as the proportion of the two organisms present vary. The red- 

 dening organisms are found on practically all sea salts. Mined salts are free 

 from infection with these undesirable bacteria. But as all fish-salting establisliments 

 are thoroughly infested with the organisms, a change to salts free from infection 

 with these undesirable bacteria would not be effective in removing the difficulty 

 unless the plants were thoroughly disinfected. 



A Method of Salting Fish in Warm Climates 



At one time the problem of salting fish in warm climates was a very difficult 

 one. Many fishermen have attempted commercial salting of river herring and 

 other fish in Florida, but were never successful until certain improvements in salt- 

 ing methods were discovered. Changes in the old commercial methods came as a 

 result of careful consideration of the physical and chemical principles of fish 

 salting and extended researches carried out at the Bureau of Fisheries, with the 

 cooperation of Johns Hopkins University and many commercial fish-salting estab- 

 lishments. The solution of this problem is a matter of economic importance as it 

 permits the cheap preservation of large quantities of fish in Florida, southern Cah- 

 fornia, Brazil, and many other tropical and semitropical regions. The researches 

 upon which the process and improved methods are based have been described 

 by Tressler (1920) and Taylor (1921). The cardinal points of the process are 

 outhned in the following: 



After capture the fish should be carefully handled and immediately iced. All 

 viscera and blood must be removed in cleaning. This point is most important as 

 the blood remaining in fish will sour if the average temperature is above 68° F 

 (20° C), whereas fresh fish free from blood can be salted at 91° F (32.8° C), or 

 higher. After cleaning it is well to remove the last traces of blood by washing with 

 ice water for a half hour or longer. 



All large fish should be split before being salted. An ample quantity (35 pounds 

 per 100 pounds of fish) of fine dry salt should be used in packing the fish into 

 watertight containers. No brine should be used and the salt should be of the 

 highest purity obtainable at a reasonable price as appreciable amounts of calcium 

 and magnesium in common salt retard its penetration. 



The fish should be rolled in salt prior to packing and a uniform quantity 

 sprinkled over each layer. The length of time required for the salting of fish, ac- 

 cording to previous directions, varies with the temperature and the size of the 

 fish. Small fish such as the alewives can often be salted or "struck through" in two 

 days. 



Fish salted as described are entirely free from the strong taste of most salted 

 fish, caused by calcium and magnesium salts retained in the freshened fish and 

 by the slightly soured blood. Moreover, they are soft and flexible and freshen 

 quickly, producing a fish resembling fresh fish in many ways. Salt fish, free from 

 blood, keep much better than similar fish containing blood or entrails, and 

 may be stored in much warmer storehouses. The temperature at which such fish 



